Stair system with expandable center

ABSTRACT

A staircase assembly comprising a plurality of stringers, and; a plurality of stair units, having treads and risers wherein stair unit is secured by means of fastening means on each corner to said plurality of stringers, said stringers, having a diagonally shaped series of equally spaced substantially vertical structure notched out of one side to define the length and height of each step of the stair assembly. The said tread,-forming a channel by rolling the leading edge for holding the riser of the stair unit installed immediately below, and each stair unit is secured by means of fastening means on each corner to said plurality of stringers, said channels further engaging other stair unit laterally sliding for providing horizontal adjustability.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from the provisional application No.60/583,203 filed on Jun. 28, 2004. The applicant filed a disclosuredocument on 12 Sep. 2003; Ser. No. 541,502.

STATEMENT REGARDING COPYRIGHTED MATERIAL

Portions of the disclosure of this patent document contain material thatis subject to copyright protection. The copyright owner has no objectionto the facsimile reproduction by anyone of the patent document or thepatent disclosure as it appears in the Patent and Trademark Office fileor records, but otherwise reserves all copyright rights whatsoever.

FIELD OF INVENTION

This invention generally relates to a staircase system, morespecifically to an adjustable staircase system and, still more preciselyto a staircase system with expandable center that is easily and quicklybuilt, cost effective and is safe to be installed by an average worker.

BACKGROUND OF THE INVENTION

A major cost portion of any construction project, whether residential,commercial, or industrial, is that of stair construction. Thespecialized nature of stair construction, coupled with the multitude ofindividual pieces that may fit exactly, various building codes that maybe met and the various materials that can be used, make it necessary touse highly skilled craftsmen to design and construct stairs. Thesecraftsmen are necessary whether building one stair or multiple stairs ofthe same design, because of the small variations between floor heights,and floors may lead to a not so perfectly level or square. Accordingly,the need has arisen, for the development of the Stair System whichprovides the flexibility of expansion in height and length and at a lowmaterial and labour cost.

U.S. Pat. No. 5,890,330 discusses an adjustable staircase system; whereadjustable steps extend between two parallel stringboards. Eachstringboard includes two locking flanges and each step is supported byfour pivotable blocks each securable to a flange by means of a nut. Twothreaded rods extending through the step and between the stringboardsengage two respective nuts combined with two opposite blocks. The heightof each step of the staircase may be adjusted by changing the spacingbetween the blocks along each flange. The horizontal position of thesteps may be adjusted by changing the vertical distance between thefront blocks and rear blocks along the stringboards, regardless of theangle at which the stringboards were fitted. A universal staircase maythus be achieved. Considering various aspects this system is limited inmany ways as pivotable blocks make the assembly bulky and costly withoutadded benefit adding towards extra installation time.

In another U.S. Pat. No. 5,636,483 a system is discussed where aprefabricated stair system having individually pivotally mounted rightangular brackets on opposed stringers, has a control bar which removablecontacts the brackets to assume all brackets are arranged at the sameangles with respect to the stringer so that the treads, which aresupported by opposed pairs of brackets, are parallel to the floors andthe risers supported by the brackets are perpendicular to the treads.The stair system is shipped as a kit and assembled in situ following amethod of assembly and installation. This system as the system is madeto order and thus limited in its scope in various ways and having manycomponents making the assembly complicated and time consuming forinstallation.

The above mentioned prior arts and some other related works are eitherexpensive or cumbersome for assembly and require highly skilledcraftsman to design and construct stairs and thus they are timeconsuming in construction and increasing the labour cost as well. Sothere is a need for a low cost and a simple adjustable staircase systemwhich can be installed quickly by an average worker providing morestrength to all the stair treads.

OBJECT OF THE INVENTION

In view of the foregoing disadvantages inherent in the above-mentionedtechniques, a general object of the present invention is to obviateabove and other drawbacks associated with the prior art.

The object of the invention is to provide with a staircase system.

It is further object of the present invention to provide with anadjustable staircase system.

Another object of the present invention is to reduce the assemblingcomplexity of the system.

It is yet another object of the present invention to make the systemcost effective.

Still another object of this invention is to reduce the requiredinstallation time.

It is still another object of the invention to provide with anattachment of a temporary handrail.

SUMMARY OF THE INVENTION

One aspect of the present invention is a staircase assembly comprising aplurality of stringers, and; a plurality of stair units, having treadsand risers wherein stair unit is secured by means of fastening means oneach corner to said plurality of stringers.

Said stringers, having a diagonally shaped series of equally spacedsubstantially vertical structure notched out of one side to define thelength and height of each step of the stair assembly.

The said tread, forming a channel by rolling the leading edge forholding the riser of the stair unit installed immediately below, andeach stair unit is secured by means of fastening means on each corner tosaid plurality of stringers, said channels further engaging other stairunit laterally sliding for providing horizontal adjustability.

A staircase assembly further comprising tread having catching holes at apredetermined distance that is identified according to the length of thestaircase, and a handrail assembly having a handrail posts, securingmeans, and rails, handrail post designed for fixing to the holder ofsaid stringers through the catching holes of said treads and securingmeans are configured for clamping this assembly tightly to saidstringers.

According to the another aspect of the invention an adjustable staircaseassembly having a plurality of stairs each stair having a base unithaving a receiving grove at its angled corner, and a stair unit having afirst projecting structure, a curved structure and a second projectingstructure, for fixing on top of said base unit, characterized in thatthe said first projecting structure is configured for fixing it into thesaid receiving grove of the base unit, and the curved structure isconfigured for clamping the said second projecting structure of a secondstair to form a staircase assembly.

The invention described herein is not limited to above description, anyother embodiment implementing the concept of instant invention will fallunder the scope of the present invention and will be the subject matterof the protection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the stair system with expandable center;

FIG. 2 is an inside or left-hand view of the stair system withexpandable center with an exploded view of the bottom stair unit showinggreater detail, according to a preferred embodiment of the presentinvention;

FIG. 3 is an opposing perspective view of the stair system withexpandable center, with an exploded view of the bottom stair unitshowing greater detail;

FIG. 4 is a piecemeal view of the stair system with expandable center,prior to final installation;

FIG. 5 is a perspective view of a stair unit; and

FIG. 6 is a side view of a stair and base unit attached together,according to an alternate embodiment of the present invention.

REFERENCE NUMERALS

-   20 . . . outer stringer-   25 . . . central stringer-   31 . . . riser-   32 . . . tread-   33 . . . corner bend-   34 . . . lip-   35 . . . bolt hole-   36 . . . handrail aperture-   37 . . . lap seam-   41 . . . handrail post-   42 . . . post receptacle-   43 . . . bracket-   44 . . . handrail system-   46 . . . first projecting structure-   48 . . . receiving grove-   50 . . . second projecting structure

DETAILED DESCRIPTION OF THE DRAWINGS

A further understanding of the present invention may be obtained withreference to the following description taken in conjunction with theaccompanying drawings. However, the embodiments used for describing theinvention are illustrative only and no way limiting scope of theinvention. A person skilled in the art will appreciate that many moreembodiments of the invention are possible without deviating from thebasic concept of the invention any such embodiment will fall under thescope of the invention and is a subject matter of protection.

FIG. 1 is a perspective view of the stair system with expandable centershown as a complete built system of its components.

FIG. 2 shows the left-hand side view of the stair system where DETAIL Ashows the configuration of the individual stair units and theirrelationship to each other.

FIG. 3 is a front perspective view of the stair system and illustratesthe sliding engagement between two individual stair units and the cornerbent 33 so created. DETAIL B provides greater detail of the attachmentpoint of the handrail system 44, specifically the handrail post 41secured within the post receptacle 42. The handrail system 44 compriseshandrail posts 41, brackets 43, and rails and is generally tubular onshape and lightweight, yet resilient in construction. The postreceptacle 40 is designed to receive the handrail post 41 and iscylindrical is shape with one open end and means to lock the handrailpost 41 in place. The inner diameter of the receptacle 42 is slightlylarger than that of the handrail post 41 and is constructed of similarmaterials. A bracket 43 is affixed to the inner wall surface of theright-hand stringer 20 to retain the post receptacle 42 to said stringer20.

FIG. 4 shows the stringer boards 20, 25 that are typically adiagonal-shaped device with a series of 90° angles notched out of oneside to define the length and height of the tread 32 and riser 31portions of the stair system. The stringer boards 20, 25 should all beof equal shape and size and utilize conventional mechanical fastenerswhen installed to the building framework.

FIG. 5 shows the stair units should all be of equal shape and size. Thestair unit is bent at a 90° angle making a corner bend 33 which definesthe tread 32 and riser 31 to match that of the tread and riser cut-outson the stringers 20, 25. The leading edge of the tread 32 is formed intoa lip 34, or “C”-channel which doubles back against itself to a pointupon which the clearance between the lip 34 and the riser 31 portion ofthe stair unit installed immediately below. The lip 34, of individualstair units 34 are designed to sliding engage each other laterally,thereby defining a left- and right-hand stair unit. Both left-hand andright-hand stair units have bolts holes 35 drilled there through on theleft side and right side, respectively for affixing the stair unit toits respective stringer 20. The right-hand stair units also have anaperture 36 drilled there through at the bottom, top, and every seventhor central stair unit to accommodate the handrail system 44.

FIG. 6 illustrates an alternate embodiment of the stair system. Thestair assemblies here include two separate units, riser 31 and a tread32, a retaining clip to connect two stair units together, and a slidingassist piece. DETAILS A and DETAILS B show the bends and configurationfor the riser and stringer, as well as the shapes of the secondprojecting structure 50 and lip 34. The material of construction for thebase and stair unit may be the same as is shown in FIG. 5 and theretaining clip and sliding assist piece for vibration dampening andminimal friction may be an ultra-high molecular weight (UHMW)polyethylene or other material with the same properties. DETAILS A and Bshow the bends and configuration for the stair and base units, as wellas the shapes of the retaining clip and sliding assist piece.

The preferred embodiment of the present invention is designed to be usedby a normal person with some skills and minimal training necessary.

The stair system with expandable center 10 is designed for thefabricator or building contractor in mind. Custom building flights ofstairs can take a lot of time that could be used to complete othertasks. Therefore, a reliable and easily constructed modular stair systemthat can fit any situation such as is presently defined can become agreat time and resource saver.

The present invention is designed to be prefabricated off-site accordingto the general specifications of the construction and transported to thesite for final fitting and finishing in the space provided. The firststep is measuring the total height and width by laying out the rise andrun of the stringers 20, 25 that will be cut. The height is determinedby the measured distance between the finished bottom floor to the top ofthe upper deck and the width is generally determined by standardbuilding codes. Two (2) outside stringers 20 and a third centralstringer 25 are identically cut to form the support structure of thestair units 30.

The next step required is to form the tread 32 and riser 31 from thesheet stock of the stair unit 30 to the required shape. A 90° angle isneeded to define the boundary 33 of the tread 32 to the riser 31. On theopposite end of the tread 32 from the bend 33, a lip 34 is formed byrolling the leading edge about a radius and doubling back against itselfcreating a “C”-shaped channel, through which another stair unit 30similarly formed can slide therethrough. The backwards bend of the lip34 should result in minimal clearance between the lip 34 and thefront-facing surface of the top of the riser section 31 of the bottomstair unit 30. Apertures or slots 35 are then formed at spaced intervalsnear the same edge of the tread 32 and riser 31 to accommodate nails orbolts. Care must be taken here to form identical stair units 30. Half ofthe stair units 30 should have the formed bolt holes 35 on its rightside (see FIG. 5) and the other stair units'bolt holes 35 formed on theleft side. Also, the handrail pole aperture 36 is cut out on a desiredside of the tread 32 of every seventh stair unit 30 as per OSHAguidelines (see FIG. 5), and ensuring that the bottom, top, and at leastone central stair unit 30 are included.

At this point, the finished stair units 30 should be secured to the topand front surface of the stringers 20, 25. Handrail pole receptacles 42are mounted on brackets 43 are to be installed on the inside surface ofthe stringer 20 at locations corresponding to the bottom step, top step,and seventh or central step at a position below the projected placementof the stair unit 30 (see FIG. 3, Detail B). Edge and pressure blockingmay at this time be attached at the top and bottom of each stringer 20for use during final installation. The pre-fabrication of the stairsystem with expandable center 10 is now ready for transport to thejob-site, along with the central stringer 25 and handrail system 44.

When the pre-fabricated stair system 10 has been delivered to the jobsite and placed in the space provided, final installation of the device10 should commence (see FIG. 4). The right and left sides of the system10 are adjoined together by overlapping the “C”-channels 34 of thetreads 32 of one side overtop the other side, providing a slidingengagement between the two (2) sides. It is important at this stage toensure that the side with the temporary handrail pole apertures 36 areon the outside edge as opposed to abutment of the stair system 10against a wall. One side of the stair system 10 should be secured to thebuilding framework with the other side manipulated into place by slidingthe entire side until it abuts the framework on the opposite side, atwhich point it is secured thereto. The central stringer 25 is thensecured at a central point underneath the stair system 10 by bolts,screws, or nails driven through the tread 32 and riser 31 portions ofthe overlapping stair units 30, preferably in the same pattern as usedto secure the separate stair units 30 to their respective stringer 20.Any height adjustment is inherently minimal due to building coderegulations on riser 31 height and are accounted for by the overlap andbend of the lip 34 formed at the leading edge of the tread 32 portion(“C”-channel) during prefabrication.

The handrail system 44 is then installed where needed by feeding thepoles 41 through the apertures 36 located on the tread 32 and securedwithin the receptacle 42 mounted to the inside of the stringer 20 via abracket 43 by a channel lock or similar system. A similar securingsystem is present for installing the handrails to the pole 41. Both thehandrails and poles 41 may be expandable as necessary. This handrailsystem 44 is necessary due to OSHA requirements and may be easilyremoved and the apertures 56 covered with a cap or plug when thehandrail system 44 is not installed.

Additional finishing for the handrail system 10 is generally left up tothe building fabricator or stair constructor but typically involves theuse of an adhesive or coating to protect the stair system 10 and tocover, protect, and level the lap seam 37 formed during finalinstallation. It is conceived that an adhesive tape will be applied tothe lap seam 37 to effect a smooth transition for carpet applications.Edge and pressure blocking for final construction may be attached duringpre-fabrication or during final installation.

It is conceivable that other alternate embodiments for the presentinvention may provide additional support and ease of construction. A“T”-channel piece designed for attachment directly to the top surface ofeach stringer step, with the extended piece fitting within a similarlyshaped and sized notch formed downward from the top surface of saidstringer step, provides added support for the stair units.

A more elaborate design involving a separate tread and riser stair unitand base unit with more bends are referred to in FIG. 6. The slidingpoint in particular has a separate rounded extension piece offset fromthe corner bend defining the riser and tread boundary and running theentire width of said boundary. This rounded piece is received within asimilarly yet opposite shaped groove on the base unit. The base unit isplaced first on top of the top and front facing stringer surfaces andthe tread and riser stair unit is placed on top of the base unit, withthe vertically interlocking pieces corresponding to specialized bends atthe leading edge of the tread portion. Vibration dampening devices suchas UHMW polyethylene fill in the space and secure said stair units andbase units together at the lip joint and at the sliding point to providea smoother movement between the lateral stair units.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated.

1. A staircase assembly comprising: a plurality of stringers having adiagonally shaped series of equally spaced substantially verticalstructure notched out of one side to define the length and height ofeach step of the stair system; and a plurality of stair units, havingtreads and risers wherein said tread forming a channel by rolling theleading edge for holding the riser of the stair unit installedimmediately below, and each stair unit is secured by means of fasteningmeans on each corner to said plurality of stringers, said channelsfurther engaging other stair unit laterally sliding for providinghorizontal adjustability.
 2. A staircase assembly as define in claim 1wherein said assembly further comprising treat having catching holes ata predetermined distance of the staircase system and a handrail assemblyhaving a handrail posts, securing means, and rails, handrail postdesigned for fixing to the holder of said stringers through the catchingholes of said treads and securing means are configured for clamping thisassembly tightly to said stringers.
 3. A staircase assembly as definedin claim 1, wherein said stringer further comprising holders at firstpredetermined distance holder is cylindrical in shape and is open fromthe top to lock the handrail post in place.
 4. A staircase assembly asdefined in claim 1, wherein said first predetermined distance isidentified according to the length of the staircase.
 5. A staircaseassembly as defined in claim 1, wherein said riser having a juttingprojection for holding said tread of immediate upper stair unit.
 6. Anadjustable staircase assembly system comprising: a plurality of stairseach stair having a riser having a receiving grove at its angled corner,and; a tread having a first projecting structure, a curved structure anda second projecting structure, for fixing on top of said base unitwherein said first projecting structure is configured for fixing it intothe said receiving grove of the base unit, and the curved structure isconfigured for clamping the said second projecting structure of a secondstair to form a staircase assembly.
 7. An adjustable staircase assemblyas defined in claim 6, wherein said assembly further comprising anadjustable central support frame for supporting stairs.
 8. An adjustablestaircase system as defined in claim 6, wherein said assembly mayoptionally be provided with a railing.
 9. A method of constructingadjustable stairs between a floor and a deck, comprising the steps of:measuring a distance the floor and the deck located above the floor;cutting stringers in accordance with information gathered in saidmeasuring step, forming treads and risers to substantially securely matewith said stringers to produce a finished stair unit; and securing saidfinished stair unit to the floor and the deck.